Counting unique elements in an array in JavaScript

We are required to write a JavaScript function that counts all unique items in an array. The function should return an object representing the count of each unique element of the array.

Therefore, let’s write the code for this function −

Example

The code for this will be −

const arr = ["hi", "hello", "hi"];
const countUnique = arr => {
   const counts = {};
   for (var i = 0; i < arr.length; i++) {
      counts[arr[i]] = 1 + (counts[arr[i]] || 0);
   };
   return counts;
};
console.log(countUnique(arr));

Output

The output in the console will be −

{ hi: 2, hello: 1 }

AmitDiwan

Published on 24-Oct-2020 11:52:00

• Related Questions & Answers
• Counting below / par elements from an array - JavaScript
• Unique number of occurrences of elements in an array in JavaScript
• Counting possible APs within an array in JavaScript
• Count unique elements in array without sorting JavaScript
• Counting frequencies of array elements in C++
• Counting elements of an array using a recursive function in JS?
• Finding unique string in an array in JavaScript
• Counting number of triangle sides in an array in JavaScript
• How do I make an array with unique elements (remove duplicates) - JavaScript?
• C program to find the unique elements in an array.
• Sorting array of exactly three unique repeating elements in JavaScript
• JavaScript Count the number of unique elements in an array of objects by an object property?
• Counting the occurrences of JavaScript array elements and put in a new 2d array
• Extract unique values from an array - JavaScript
• Counting n digit Numbers with all unique digits in JavaScript